Discrete Rainfall Predictability Using the El Niño/Southern Oscillation Interaction

• Activity Number: 81
• Type: Contributed
• Date/Time: Sunday, August 4, 2013 : 4:00 PM to 5:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Luis Cid-Serrano*+ and Sandra Ramirez-Buelvas and Eric Alfaro and Sergio Contreras
• Companies: University of Bio Bio and P. Universidad Javeriana de Cali and Universidad de Costa Rica and University of Bio Bio
• Keywords: El Niño ; Southern Oscillation ; Logit regression ; Rainfall

Abstract

The objective of the study is to determine the probability of occurrence of wet or dry climatic events, based on the El Niño/Southern Oscillation (ENSO) phenomenon using multinomial logit regression models. The study used monthly time series of the Pacific equatorial sea surface temperature (SST), a sea level pressure index (SOI) and rainfall anomalies over a 2.5x2.5 degrees grid along the west coast of Central and South America, for latitudes starting at 25N, through 45S, since 1951. We defined an ENSO index (NSO) as predictor and rainfall as response. Data was categorized into terciles to construct non symmetrical three way contingency tables. As results, we generated latitudinal profiles of the predictability (association), for the West Coast of Central and South America, using ENSO as predictor.